Weeds can be so very sneaky; getting into the weirdest places, and taking on all sorts of forms. They are mostly annuals or perennials that infest lawns and beds, but can be shrubs, vines and even big trees that grow among desirable plants, in untended areas, in cracks in pavement and even in roof gutters and on flat roofs. Many look appealing at first, but then later get out of control and displace the plants around them, or wreck whatever fence, pavement or building they encounter. Heck, I even suspect that it was a weed that stole my neighbor’s Pontiac!

While the soil is still damp from earlier rain, the most common annual weeds that are just developing are easiest to pull. They will put up more of a fight later, after they have dispersed roots, and the soil has gotten a bit more firm. Perennial weeds that were already established before winter will be considerably more stubborn, but not as stubborn as they will be as the soil dries later. Bermuda grass and crabgrass are always nasty.

The biggest, sneakiest and most stubborn weeds are ironically descendents of substantial perennials, shrubs and trees that were once actually planted in gardens. They are sneaky because they look as pretty as their parents when they first appear, in order to dissuade us from pulling them. The problems are that they are often too abundant, and very often get into spots where they will be problematic as they grow.

For example, Acacia dealbata and black locust are rather appealing trees while they are young, especially when they bloom. This is why they were originally planted in local gardens. It is tempting to allow self sown seedlings to grow instead of pulling them when they first appear. However, because they were not actually planted strategically where they can necessarily be accommodated, they grow in random situations, too near to pavement, fences or eaves, or in areas that are already landscaped. As they mature, they can damage these features or the plants around them.

Privet, pampas grass, castor bean and a variety of palms, acacias, ivies and several other plants that do a bit too well in local gardens have certain potential to become invasive or aggressive big weeds. Tree of Heaven, giant reed, the various brooms and the most invasive of acacias  have not been available in nurseries for many years because they are so problematic, but continue to be some of the most invasive and aggressive weeds in California.

While it was busy naturalizing in Australia, South Africa and southern South America, the California poppy was getting forced out of parts of its own native range by more aggressive exotic plants that were also busy getting naturalized. Technically, any plant that is not native is exotic. Any exotic plant that becomes naturalized in a foreign environment is able to proliferate without any help, as if it were native. Naturalized exotic plants that get too aggressive become invasive weeds.

Weeds are plants where they are not wanted. This is a very broad definition that includes plants ranging from simple little dandelions in urban lawns to humongous bluegum eucalyptus in forests. Naturalized exotic weeds can be much more problematic than weeds that can only proliferate where they get watered in gardens and landscapes, because they can get established where they are not expected.

Water hyacinth that clogs the Sacramento and San Joaquin River Delta is not often a problem in terrestrial landscapes. However, giant reed, pampas grass, Acacia dealbata and blackberry brambles can infest home gardens just as easily as they infest wild lands. Because they do not need to be watered, they can get established and grow quite large in unused parts of the garden before anyone notices.

Many naturalized weeds somehow seem to much more aggressive and problematic than even the most prolific of native plants. Even the common native lupines are relatively docile compared to annual oat grass. Native blackberry may seem impossible to eradicate, but is actually neither as persistent nor as unpleasant to handle as the exotic Siberian blackberry!

Young weeds are easiest to pull now while the soil is still evenly damp, and young roots are only beginning to disperse. They will be more difficult to pull after roots are dispersed and soil hardens. Tree weeds and large perennial weeds that were cut down last year instead of pulled will likely need to be dug. Bermuda grass is a relatively low perennial grass that always seems to be difficult to dig. Mowing or cutting down annual grass weeds with a weed whacker will not eliminate them, but limits the development and dispersion of seed for the next generation. Burclover, sowthistle, bindweed, purslane, spurge and the various oxalis are some of the other common weeds that really get going this time of year.